1. Field of the Invention
This invention relates to the processing of slag in the manufacture of mineral wool.
2. Description of the Art Practices
The manufacture of steel results in slag being formed. Slag is an agglomerate that floats to the surface of the steel. The slag includes impurities in the ore, the fuel and the blast furnace lining. Slag is useful in preparing mineral wool which is formed by blowing air through a molten mass of slag. Mineral wool is used in fireproofing applications and for insulation.
Typically slag is composed of silica, alumina, lime and magnesium oxide. The usual manner of obtaining mineral wool is by placing the slag into a furnace. Usually large chunks of the slag weighing several hundred pounds are the preferred raw material. It has been observed, however, that through the handling of the slag that smaller chunks of the slag break off which are in the range of a few grams to a few hundred grams. This slag is essentially a waste material as it is difficult to process into the furnace. For unknown reasons, the large chunks of steel slag in the blast furnace tend to slowly and uniformly be released into the molten form.
The obvious solution of dumping the fine slag into the furnace results in a plating out of the slag on the bottom of the furnace. When the slag plates out on the bottom of the furnace, the first effect is that the slag is no longer available for mineral wool manufacture. Secondly, the build-up of the slag causes ineffective heat transfer in the furnace thereby requiring greater thermal energy and eventually requiring a shut-down of the furnace to remove the built-up slag.
It therefore remains to present a solution to utilize fine slag which is otherwise acceptable for mineral wool manufacture.
It is known that starches may be utilized to enhance the strength of charcoal briquets. Typically, the moisture content of an undried charcoal briquet will be in the range of from 15% to 25% of the total briquet weight and under 5% in the dried briquet.
Throughout the specification and claims percentages and ratios are by weight and temperatures are in degrees Celsius unless otherwise indicated.